Ever since the Nuremberg Tribunal delivered its historic judgment, the principle of individual criminal liability for the unlawful use of force has been characterized by an unbridgeable gap between theory and practice. With the exception of the post-war trials against World War II enemies, the trial and punishment of individual perpetrators has never been seriously contemplated in response to violations of the jus ad bellum, not even in the face of the most egregious aggressions. At a time when the practical import of the "supreme crime" seemed to have fallen into oblivion, its inclusion alongside the other core crimes within the Rome Statute not only reignited the debate on this topic, but, more importantly, mobilized unparalleled resources in order to pass from words to deeds. After years of intense work, in February 2009 the Special Working Group on the Crime of Aggression, established under the auspices of the Assembly of States Parties, completed its mandate and submitted a series of Draft Amendments to be considered at the first Review Conference, to be held in Uganda some time in the first half of 2010. If only for this reason, taking stock of the law governing individual criminal liability for the unlawful use of force is both appropriate and timely. Looking at the abundant scholarly works that exist on the jus ad bellum and aggression as a "state crime" - two true classics of international law over the past few decades -, one cannot help but puzzle over how little is known, in comparison, about aggression as an individual crime. This thesis fills this identified gap in the legal literature, first of all by providing a comprehensive study of the law governing the crime of aggression as it emerges from the post-war jurisprudence and, secondly, by taking stock of the last decade of diplomatic negotiations in the light of said regime.